Question

State the reason why carbon can neither form C4+ cations nor C4− anions but forms covalent compound. Also state the reason to explain why covalent compounds: (i) are bad conductors of electricity. (ii) have low melting and boiling points.

Answer 1

Atomic number of carbon is six. This means that it has four electrons in its outermost shell and it needs four more electrons to attain noble gas electronic configuration. It does not form C4+ cation, as the removal of four valence electrons will require a huge amount of energy. The cation formed will have six protons and two electrons. This makes it highly unstable. Carbon is unable to form C4− anion as its nucleus with six protons will not be able to hold ten electrons. Thus, carbon achieves noble gas electronic configuration by sharing its four electrons with other elements, i.e. it forms covalent compounds.
(i) Covalent compounds are bad conductors of electricity due to lack of free electrons.
(ii) Covalent compounds are formed by covalent bonds and it has been found that the intermolecular forces of attraction in covalent compounds are weak. Thus, their melting and boiling points are quite low.

Answer 2

Carbon can neither form C4- nor C4+ because for the following reasons::

The atomic number of carbon is six. so the electric configuration of carbon is 2,4 hence it has four electrons in its valence cell. If it losses it's four electrons (C4+)then it requires a lot of energy.

It is unable to form C4- because carbon is unable is unable to form C4- anion as it's nucleus with six electrons will not be able to hold ten electrons. Thus carbon achieves noble gas electronic configuration by sharing it's electron with other atoms...

1) Due to lack of electrons in covalent compounds they are bad conductor of electricity.

2)The intermolecular force of attraction in covalent compounds are week. So they have low melting and boiling point.

Hope it may help you....